The present invention relates generally to a method for producing a soluble form of lipophilic compounds such as carotenoids and, more specifically, to an emulsion containing high levels of liposome-encapsulated carotenoids, such as lutein and zeaxanthin, suitable for the use in pharmaceutical products, medical devices, and food industry.
Although no directives or guidelines exist regulating the indication of raw materials when developing a new pharmaceutical product, pharmaceutical grade substances should be used whenever possible.
Lutein is used in the pharmaceutical industry (in medical devices) and also as a coloring agent for a variety of foods and beverages (Scotter M J. 2011. Methods for the determination of European Union-permitted added natural colours in foods: a review. Food Additives and Contaminants. 28(5): 527-596). The natural form of lutein is in crystals. In consequence, it is insoluble in several dilution systems, which makes difficult its application in tableted products, medical devices and food related products. Soluble forms of crystalline lutein were developed, such as the so-called “Cold Water Soluble Lutein” (CWSLutein). However, this food-grade material presents some limitations, including formation of sediments that become visible after one or two days in solution. Sedimentation is probably due to other constituents of that raw material, which also include starch, glucose syrup and ascorbic acid. In addition, the presence of these substances hampers lutein release mainly due to the formation of a rigid polysaccharide-like structure (Amar I, Abraham A and Garti N. Solubilization Patterns of Lutein and Lutein Esters in Food Grade Nonionic Microemulsions. 2003. J. Agric. Food Chem. 51:4775-4781). Instability to light exposure is another problem of CWSLutein, as all products produced with this raw material need to be supplied in amber containers or kept in dark conditions. Therefore, the development of a pharmaceutical-grade, soluble, dispersible and stable carotenoid-containing raw material is an urgent need.